GB862428A - Method and apparatus for forming fibers - Google Patents

Abstract

<PICT:0862428/IV (a)/1> <PICT:0862428/IV (a)/2> Fibres are formed from thermoplastic macromolecular substances which cannot be formed into fibres by conventional extruding and drawing processes by discharging the molten substance under pressure from one or more nozzles into an atmosphere which is maintained at a temperature below the melting point but above the embrittlement point of the substance to form a stream or streams of the molten substance, at least partially setting the stream, or each stream, by cooling it, attenuating and disrupting the partially set stream or streams by means of a high-velocity stream of gas or by passing the partially set stream or streams into a zone of turbulent gas to form fibres, collecting the fibres and cooling them. Instead of being in the molten state the substance may be in solution in a volatile organic solvent and the stream may be set by evaporation of the solvent by the gas. The substances to be converted into fibre form may be asphalts, bitumens and pitches derived from petroleum or coal; natural resins and gums such as rosin, gum dammar, gelatin, glue, agar-agar, gum tragacanth and gum elemi; waxes such as paraffin, carnauba and beeswax; synthetic polymers of the non-conventional fibre-forming type, i.e. having a molecular weight below 10,000, such as polystyrene, polyethylene of molecular weight below 7000, polyvinyl acetate; polyamides and polypeptides such as partially hydrolized natural proteins, e.g. casein, zein, and soya protein, and inorganic thermoplastic substances such as sulphur. As shown in Fig. 1, the substance to be converted into fibre form is fed in molten condition through the conduit 7 into the manifold 7a extending transversely across the chamber 1 and communicating with a number of tubes 8 spaced along the manifold and each terminating in a spraying nozzle 8a. Preheated gas under pressure is supplied through the conduit 9 into a manifold 9a extending transversely across the chamber 1 and communicating with a number of gas tubes 10 spaced along the manifold and each terminating in a gas nozzle 10a. The gas is discharged from each of these nozzles in the form of a non-converging high-velocity stream while at the same time the molten plastic is discharged into the stream of gas in the form of a single, relatively large-diameter stream. Each stream of gas attenuates each stream of molten plastic and also breaks the attenuated stream into fibres of varying length which are deposited and collected on the inclined endless wire-mesh collector belt 3 backed with a suction chest 4. A low-velocity secondary stream of gas to carry the fibres until they are collected is supplied by the blower 11. The chamber 1 is maintained at the required temperature by steam coils 5, 6. The foraminous belt 3 carries the mat or web 12 from the chamber 1 through a cooling chamber 13. As shown in Fig. 3, the plastic in granular or pellet form is fed from hopper 25 by a rotating screw 26 into the rotating hollow disc 17, 18, 20 via the rotating hollow shaft 21. The disc is heated electrically by means of a current supplied by means of slip rings and brushes to a temperature sufficient to melt the plastic, which is discharged under the centrifugal force generated by the rotation of the disc through a number of radially extending spaced spraying jets 19. The streams of molten plastic are converted into fibre form by the zone of turbulent gas generated by the vanes 22 mounted on the rotating hollow disc. The rotating hollow disc 17-20 is positioned within a chamber 15 provided with heating coils 16 and an endless travelling foraminous belt 27 upon which the fibres may be collected in a layer, which is then passed through the cooling chamber 28 and collected on the reel 29. Laminates bound together by adhesive fibres may be formed simultaneously with the production of the fibres (see Group VIII). Specifications 794,725, 795,034 and 827,641 are referred to.ALSO:<PICT:0862428/III/1> <PICT:0862428/III/2> Sulphur is converted into fibrous form by discharging molten sulphur under pressure from one or more nozzles into an atmosphere which is maintained at a temperature below the melting point but above the embrittlement point of the sulphur to form a stream or streams of the molten sulphur, at least partially setting the stream or each stream by cooling it, attenuating and disrupting the partially set stream oor streams by means of a high velocity stream of gas or by passing the partially set stream or streams into a zone of turbulent gas to form fibres, collecting the fibres and cooling them. Instead of being in the molten state the sulphur may be in solution in a volatile organic solvent and the stream may be set by evaporation of the solvent by the gas. As shown in Fig. 1, the sulphur is fed in molten condition through the conduit 7 into the manifold 7a extending transversely across the chamber 1 and communicating with a number of tubes 8 spaced along the manifold and each terminating in a spraying nozzle 8a. Preheated gas under pressure is supplied through the conduit 9, into a manifold 9a extending transversely across the chamber 1 and communicating with a number of gas tubes 10 spaced along the manifold and each terminating in a gas nozzle 10a. The gas is discharged from each of these nozzles in the form of a nonconverging high velocity stream while at the same time the molten sulphur is discharged into the stream of gas in the form of a single, relatively large-diameter stream. Each stream of gas attenuates each stream of molten sulphur and also breaks the attenuated stream into fibres of varying length which are deposited and collected on the inclined endless wire-mesh collector belt 3 backed with a suction chest 4. A low velocity secondary stream of gas to carry the fibres until they are collected is supplied by the blower 11. The chamber 1 is maintained at the required temperature by steam coils 5, 6. The foraminous belt 3 carries the mat or web 12 from the chamber 1 through a cooling chamber 13. As shown in Fig. 3, the sulphur in granular or pellet form is fed from hopper 25 by a rotating screw 26 into the rotating hollow disc 17, 18, 20 via the rotating hollow shaft 21. The disc is heated electrically by means of a current supplied by means of slip rings and brushes to a temperature sufficient to melt the sulphur, which is discharged under the centrifugal force generated by the rotation of the disc through a number of radially extending spaced spraying jets 19. The streams of molten sulphur are converted into fibre form by the zone of turbulent gas generated by the vanes 22 mounted on the rotating hollow disc. The rotating hollow disc 17-20 is positioned within a chamber 15 provided with heating coils 16 and an endless travelling foraminous belt 27 upon which the fibres may be collected in a layer, which is then passed through the cooling chamber 28 and then collected on the reel 29. Specifications 794,725, 795,034 and 827,641 are referred to.